[EricH]

Originally Posted by daniel_dsouza

Still curious, exactly how would your cannon maintain pressure during a shot, if it is belt fed? Wouldn't you loose most of your pressure through the belt slot?

Not necessarily.

You could lock down around the belt.
You could build a belt that looks like _O_O_O_O_O_O_O_O_, where the O signifies a "cartridge" that has seals on the ends and a rolled-up T-shirt in the middle. That's the basic premise behind Shockwave's revolver section maintaining most of its pressure, IIRC.
You could fire at extra-high pressure. That's a bit risky, though.